Biology Reference
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Sepal spurs are reported in most genera of Vochysiaceae, except Am-
philochia and Euphronia (Oliveira, 1996; Hodges, 1997), and in
Pelargonium (Geraniaceae; Fahn, 1979; Vogel, 1998c).
Petal spurs have been reported in some Valerianaceae s. str. (now sub-
sumed under Caprifoliaceae s.l. ) ( Centranthus ; Fahn, 1979; Wagenitz &
Laing, 1984; Rehnberg, 1987), Scrophulariaceae (Vogel, 1998b; Nepi
et al., 2003), Violaceae (Vogel, 1998b; Freitas & Sazima, 2003), the genus
Halenia (Gentianaceae; von Hagen & Kadereit, 2003), and in some Lo-
nicera species (Caprifoliaceae; Cronquist, 1981).
In Cactaceae, hypanthial spurs were reported for a species of Hildewintera
(Kiesling & Metzing, 2004).
Within the monocots, the tepals of some Orchidaceae, e.g., Angraecum ,
Gymnadenia , Habenaria , Jumellea , Limodorum , Neobathiea , and Platan-
thera (Nilsson et al., 1987; Dressler, 1990; Figueiredo & Pais, 1992; Galetto
et al., 1997; Stpiczyńska & Matusiewicz, 2001; Stpiczyńska et al., 2005)
have nectariferous spurs. Spurs can be small and inconspicuous, but can also
become the most noticeable part of the flower—the Malagasy hawkmoth-
pollinated star orchids are renowned for their 30-40 cm long spurs (Nilsson
et al., 1987).
Finally, it is worth mentioning that nectar production in spurs has to be
checked carefully, because this simple fact is rarely accurately observed and
described. In fact, it has to be confirmed whether nectar is directly produced
and accumulated in the spurs. To this end, anatomical studies are required to
ascertain whether the spurs contain secreting tissue. Spurs are slender, hol-
low structures and when nectar is secreted directly in them, the nectariferous
tissue is usually composed of unicellular trichomes or small papillae of epi-
dermal nature (e.g., Caprifoliaceae; Fahn, 1979; Orchidaceae; Galetto et al.,
1997; Stpiczyńska et al., 2005; Tropaeolaceae; Rachmilevits & Fahn, 1975).
Alternatively, nectar may be exuded from nectaries located in other floral
parts and, secondarily, be conducted to and accumulated in the spurs, as re-
corded for some Scrophulariaceae and Violaceae (Vogel, 1998b).
3.5
Patterns of variability in nectaries
Without doubt, the wealth of floral nectaries among the angiosperms is as fasci-
nating as their flowers. Nonetheless, as nectaries are diminutive structures, they
are easily overlooked or misinterpreted; as a result, their descriptions are often
inaccurate. As Davis et al. (1996) pointed out, it is common for nectaries to
be treated superficially or neglected entirely in studies of floral development
and morphology. Both microscopical sections and experimental observations
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